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Positively chargeable developer

Inactive Publication Date: 2006-07-20
CANON KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0010] Another object of the present invention is to provide a developer capable of providing stable image quality without causing any image defect even in long-term use, and an image forming method using the developer.

Problems solved by technology

As a result, performance required for toner has become sophisticated.
However, in applications in which a high speed and improved definition and improved image quality which have been required in recent years, the method is insufficient not only because developability is insufficient but also because adhesion to a charging member occurs.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0204] Binder resin C-1 100 parts by mass

[0205] Magnetic iron oxide particles (octahedron, number average particle size: 0.20 μm) [0206] 90 parts by mass

[0207] Wax b (Fischer-Tropsch wax, Table 2 shows the physical properties. Highest endothermic peak temperature: 101° C., number average molecular weight: 1,500, weight average molecular weight: 2,500) 4 parts by mass

[0208] Charge control agent A (triphenylmethane lake pigment shown below) 2 parts by mass

[0209] After the above materials had been pre-mixed by means of a Henschel mixer, the mixture was melted and kneaded by means of a biaxial kneading extruder.

[0210] The resultant kneaded product was cooled and coarsely pulverized by means of a hammer mill. After that, the coarsely pulverized product was finely pulverized by means of a pulverizer using a jet stream, and the resultant finely pulverized powder was classified by means of a multi-division classifier utilizing a Coanda effect to produce toner particles. The zeta poten...

example 2

[0226] A developer 2 was produced in the same manner as in Example 1 except that the formulation described in Table 3 was adopted (see Table 1 for a binder resin and Table 2 for a wax). The toner particles in the developer 2 were dispersed into water, and the pH of the dispersion liquid was measured. The pH was 4. Table 3 shows the physical properties of the developer thus obtained. Tables 4 to 6 show the results of the same tests as those of Example 1.

[0227] It should be noted that the pH of the dispersion liquid prepared by dispersing the toner particles according to each of Examples 3 to 7 and Comparative Examples 1 to 5 into water was 4.

example 3

[0228] A developer 3 was produced in the same manner as in Example 1 except that the formulation described in Table 3 was adopted (see Table 1 for a binder resin and Table 2 for a wax). Zinc oxide particles used instead of alumina particles as an inorganic fine powder had a zeta potential of 8.3 mV at pH=4 and a BET specific surface area of 30 m2 / g. Table 3 shows the physical properties of the developer thus obtained. Tables 4 to 6 show the results of the same tests as those of Example 1.

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PUM

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Abstract

A positively chargeable developer is provided which is capable of providing stable image quality without causing any image defect even in long-term use. The developer includes at least positively chargeable toner particles each containing at least a binder resin and magnetic iron oxide, silica and an inorganic fine powder. A unconfined yield strength at a major consolidation stress of 5 kPa of the developer is in the range of 0.1 to 2.5 kPa, and a unconfined yield strength at a major consolidation stress of 20 kPa of the developer is in the range of 2.5 to 5.5 kPa.

Description

[0001] This application is a continuation of International Application No. PCT / JP2005 / 021636 filed on Nov. 18, 2005, which claims the benefit of Japanese Patent Application Nos. 2004-335421 filed on Nov. 19, 2004 and 2004-335385 filed on Nov. 19, 2004.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to a developer to be used for electrophotography and toner jet, and to an image forming method and an image forming apparatus for visualizing an electrostatic charge image. [0004] 2. Related Background Art [0005] A large number of methods such as an electrostatic recording method, a magnetic recording method, and a toner jet method have been conventionally known as image forming methods. For example, as described in U.S. Pat. No. 2,297,691, JP-B-S42-023910, and JP-B-S43-024748, a large number of methods have been known as electrophotographic methods. A general electrophotographic method involves: using a photoconductive substance; forming ...

Claims

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Application Information

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IPC IPC(8): G03G9/08
CPCG03G9/0821G03G9/0833G03G9/0836G03G9/0837G03G9/08795G03G9/08797G03G9/09708G03G9/09716G03G9/09725G03G9/09733G03G9/09741G03G9/09775G03G5/08G03G9/083G03G9/087G03G9/097
Inventor YAMAZAKI, KATSUHISAYOSHIBA, DAISUKEFUJIMOTO, MASAMI
Owner CANON KK
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